MFC Background color

bodhisatwa bhattacharya 21

hi,

I have a question about the background color of MFC.

My code is as follows

Mainfrm.h

class C_MainFrame : public CFrameWnd
{

public:
C_MainFrame(); // Declear Constructor

};

Mainfrm.cpp

include "MFCAppRun.h"

include "MainFrm.h"

// CMainFrame

//Define Constructor

C_MainFrame::C_MainFrame() {

    HBRUSH hredBrush = ::CreateSolidBrush(RGB(255, 200, 20));   
    CString MyWindowClass = AfxRegisterWndClass(  
                          CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW ,  
                          AfxGetApp()->LoadStandardCursor(IDC_APPSTARTING),  
                           hredBrush,                                                                        //"unable to read memory".  
                          AfxGetApp()->LoadStandardIcon(IDI_EXCLAMATION));  

    Create(MyWindowClass, _T("Main Window A"), WS_OVERLAPPEDWINDOW);  
     ::DeleteObject(hredBrush);

}

when I use hredBrush as parameter of AfxRegisterWndClass,It shows me "unable to read memory".

but when i use ::CreateSolidBrush(RGB(255, 200, 20)) as parameter of AfxRegisterWndClass it works fine.

I means refer the below code:

CString MyWindowClass = AfxRegisterWndClass(
CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW ,
AfxGetApp()->LoadStandardCursor(IDC_APPSTARTING),
::CreateSolidBrush(RGB(255, 200, 20)), // work fine
AfxGetApp()->LoadStandardIcon(IDI_EXCLAMATION));

    Create(MyWindowClass, _T("Main Window A"), WS_OVERLAPPEDWINDOW);

Can Anyone please help me to understand why this is happening?

David Lowndes 4,711 Reputation points

2023-01-09T20:44:27.053+00:00

We'll need a self-contained example that reproduces the issue.
From what you've shown there, I can see no reason there'd be a problem.
YujianYao-MSFT 4,271 Reputation points Microsoft Vendor

2023-01-10T06:42:40.707+00:00

Hi @bodhisatwa bhattacharya ,

I tested the code you shared, and it doesn't have fatal error.

What error does it throw in your compiler?
David Lowndes 4,711 Reputation points

2023-01-10T15:28:34.723+00:00

There's no error there. You're being mislead by what you're seeing in the debugger display.
bodhisatwa bhattacharya 21 Reputation points

2023-01-12T03:33:21.5666667+00:00

Thanks DavidLowndes-6766 Thanks YujianYao-MSFT

I just try to change Background color in MFC. Screenshot is attached.
David Lowndes 4,711 Reputation points

2023-01-12T09:36:46.7333333+00:00

Start from a new project, add the minimal changes to reproduce the issue, then post that project on a sharing site where anyone can access it and post a link to it here.
Viorel 111.8K Reputation points

2023-01-12T10:18:35.3733333+00:00

I think that you can ignore the "<Unable to read memory>" message that is displayed in your image. It does not denote a problem. (Or it is a limitation of the debugger, not a problem in your code). Just make sure that the hredBrush value is not null.

The AfxRegisterWndClass function seems to work.
Viorel 111.8K Reputation points

2023-01-12T21:00:57.99+00:00

I think that it is happening because of DeleteObject, not due to <Unable to read memory>.
bodhisatwa bhattacharya 21 Reputation points

2023-02-02T02:49:29.19+00:00

Hi,

Can anyone help me to solve out this problem. I think DavidLowndes-6766 not understand the problem. Still, I get same message ""unable to read memory". And background color is not changed.

Thanks

bodhisatwa bhattacharya 21

Hi Viorel,

Thanks for Text.

If I define

HBRUSH hredBrush = ::CreateSolidBrush(RGB(255, 200, 20));

then

HBRUSH hredBrush = ::CreateSolidBrush(RGB(255, 200, 20));   
    CString MyWindowClass = AfxRegisterWndClass(  
                          CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW ,  
                          AfxGetApp()->LoadStandardCursor(IDC_APPSTARTING),  
                           hredBrush,                                                                          
                          AfxGetApp()->LoadStandardIcon(IDI_EXCLAMATION));  

    Create(MyWindowClass, _T("Main Window A"), WS_OVERLAPPEDWINDOW);  
     ::DeleteObject(hredBrush);

hredBrush is not able to change background color ,due to <Unable to read memory>

If I put only "::CreateSolidBrush(RGB(255, 200, 20))", insert of hredBrush in my code is work fine.

Can You Please tell me why this is happening?

Viorel 111.8K Reputation points

2023-02-02T21:24:51.4033333+00:00

As mentioned before, "I think that it is happening because of DeleteObject, not due to <Unable to read memory>".

Accepted answer

SM 416 Reputation points

2023-02-02T21:11:15.6266667+00:00

As per documentation ,
"The system automatically deletes class background brushes when the class is unregistered by using UnregisterClass. An application should not delete these brushes.".

Remove the call to ::DeleteObject(hredBrush);.

-SM
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1 person found this answer helpful.
bodhisatwa bhattacharya 21 Reputation points

2023-02-12T10:43:33.4333333+00:00

Thank You!
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MFC Background color

include "MFCAppRun.h"

include "MainFrm.h"

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